How to convert an APNs token to `String` from `Data`?

let token = deviceToken.map { String(format: "%.2hhx", $0) }.joined() 

// Define initializer extension String { public init(deviceToken: Data) { self = deviceToken.map { String(format: "%.2hhx", $0) }.joined() } } func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data!) { // Use like this: let token = String(deviceToken: deviceToken) }